Concrete repair of tubbings

ABSTRACT

A lining ( 2 ) for an inside surface of a tunnel, preferably the inside surface of tubbings, wherein it is provided in accordance with the invention that it comprises at least two layers of different tensile strength and extensibility.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of Austrian ApplicationNo. GM 285/2008 filed May 19, 2008. Applicant also claims priority andthis application is a continuation under 35 U.S.C. §120 of InternationalApplication No. PCT/EP2009/056000 filed May 18, 2009, which claimspriority under 35 U.S.C. §119 of Austrian Application No. GM 285/2008filed May 19, 2008. The international application under PCT article21(2) was not published in English.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a lining for an inside surface of tunnels,especially the inside surface of tubbings, according to the preamble ofclaim 1.

2. Description of the Related Art

In tunneling, excavation is performed either by blasting or with specialtunnel boring machines. So-called tubbings are frequently used inmechanical tunnel construction with tunnel boring machines. Theseconcerns prefabricated concrete parts which are used as lining elementsfor the inside shell of a tunnel. As a result of the different loadsthat act upon the inside shell of a tunnel such as the loads from rockpressure, water pressure, filling pressures, or the dead weight,tubbings with a thickness of 20 to 40 cm are required. These tubbingsare compiled in the course of tunnel advance by means of suitablemachines into a first outside inner shell of the tunnel. The handling ofthe heavy tubbings occurs with the help of recesses in the tubbings, theso-called erector cones, in which the respective mandrels of specialworking machines engage. The tubbings are screwed together, which occurswith the help of further recesses in the tubbings, the so-called screwpockets, in which the screws are accommodated in an obliquely lyingfashion. These recesses can have diameters of up to 20 cm. Butt jointsare further obtained between the respective adjacently disposed tubbingswhich also represent irregularities in the surface.

A lining is then fastened to the inside surface of the tubbings such asplastic seal sheeting (KDB) made of a flexible plastic material in orderto form a water-impermeable layer. The extensibility of the lining isespecially important for the reason that future movements anddeformations of the inside shell of the tunnel will not lead to anytearing of the lining and for the compensation of irregular surfaceprofiles such as those caused by elevations or depressions in thesurface of the tubbings. The fastening of this water-impermeable layerto the tubbings occurs increasingly by gluing. Although mechanicalfixing would be possible, it is rarely used in practice due to highcosts.

Finally, a concrete shell is provided for reasons of fire protectionwhich seals the inside shell of the tunnel towards the interior of thetunnel. This fire-protection shell made of concrete is usually arrangedwith light reinforcement. This leads to the problem in practice that asa result of the pressure exerted on the lining the lining is pressedinto the recesses of the surface of the tubbings such as the erectorcones and the screw pockets, which might lead to damage to the liningand thus to an impairment in the impermeability of the same. Althoughthe recesses can be filled, mortared or plugged, such a measure is verywork-intensive because an inside surface of a tunnel made of tubbingsusually comprises several thousand such recesses.

SUMMARY OF THE INVENTION

It is therefore the goal of the invention to avoid this problem bysuitable measures, especially damage to the lining and impairment of thewatertightness by the surface irregularities in the inside surface ofthe tunnel, preferably the inside surface of tubbings.

This goal is achieved by the features of claim 1. Claim 1 relates to aninside shell of a tunnel comprising a lining for an inside surface ofthe tunnel, preferably the inside surface of tubbings, with the liningcomprising at least two layers of different tensile strength andextensibility, wherein it is provided in accordance with the inventionthat the lining comprises two layers with a first layer consisting of anelastic plastic material with higher extensibility than the secondlayer, and the second layer consists of a tear-proof fabric, and thefirst layer is connected to the second layer at least in sections. Thelining can thus be optimized to meet two different requirements. On theone hand, the previously desired properties are given by the layer withhigher extensibility but lower tensile strength, and on the other handthe second layer with lower extensibility but higher tensile strengthprevents bulging of the lining into the recesses of the inside surfaceof the tunnel such as the erector cones and the screw pockets of thetubbings. The choice of tensile strength and extensibility of the layerwith lower extensibility will be adjusted to the respective requirement.If it is necessary to cover comparatively large recesses and prevent anyconsiderable bulging of the lining, higher tensile strengths or very lowextensibilities are necessary. If it is only necessary to cover the buttjoints between adjacent tubbings, a comparatively low tensile strengthand a higher extensibility can be chosen. The respective choice oftensile strength and extensibility will easily be made by the personskilled in the art with the knowledge of the surface to be coated,especially the occurring irregularities of the surface.

In accordance with a preferred embodiment, the second layer canespecially concern a polyester, polyethylene, carbon or glass-fiber gridfabric.

In accordance with a further preferred embodiment, the first layer canbe laminated or glued onto the second layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained below by reference to an embodimentshown in the enclosed drawings, wherein:

FIG. 1 shows a schematic view of a tunnel profile with a multi-layerinside shell of a tunnel, comprising a first shell made of tubbings, awater-impermeable lining, and a reinforced or non-reinforced concreteshell;

FIG. 2 shows a schematic illustration of an embodiment of the lining inaccordance with the invention with a tubbing, and

FIG. 3 shows a schematic view of a tubbing.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is made at first to FIG. 1, which shows a schematic view of atunnel profile, as was obtained by excavation by blasting or by specialboring machines which drill a tunnel tube through the rock. The tunneltube is then either provided with a layer of spray concrete or linedwith tubbings 4. These concern prefabricated concrete parts which arelifted by special working machines to the tunnel tube and are screwedtogether. Erector cones 6 are provided for this purpose on the one hand,in which the mandrels of the working machines engage in order to enablehandling with the heavy tubbings 4, and on the other hand trapezoidscrew pockets 5 which are used for accommodating the connecting screws(also see FIG. 3). The tubbings 4 which are screwed together form afirst shell 1, on which a water-impermeable lining 2 is subsequentlyfastened, mostly by means of gluing. The lining 2 concerns a flexibleplastic material such as PVC, a flexible polyolefin, a softly setpolyethylene such as VLDPE (Very Low Density Propylene), orpolypropylene. A concrete shell 3 is provided next to the lining 2,which concrete shell is usually provided for reasons of fire protection.The fire-protection concrete shell is usually provided with a lightreinforcement with a weight of approx. 1.0-2.0 kg/m². It is alsopossible to provide reinforced or non-reinforced concrete shells.

As a result of the pressure exerted on the lining 2, the lining 2 willbe pressed into the recesses of the tubbing surface without the measuresin accordance with the invention, e.g. into the erector cones 6 and thescrew pockets 5, which might lead to damage to the lining 2 and thus animpairment in the impermeability of the lining. That is why it isprovided in accordance with the invention that the lining 2 comprises atleast two layers 2 a, 2 b with different tensile strength andextensibility. The first layer 2 a with higher extensibility providesthe previously desired properties, and the second layer 2 b with thehigher tensile strength and lower extensibility prevents the bulging ofthe lining 2 into the recesses on the inside surface of the tunnel, e.g.the erector cones 6 and the screw pockets 5 of the tubbings 4. Thechoice of tensile strength and extensibility of the second layer 2 bwith lower extensibility will be adjusted to the respectiverequirements. If comparatively large recesses need to be covered withoutproviding any considerable bulging of the lining 2, very lowextensibility in combination with high tensile strength is required forthe second layer 2 b. If it is only necessary to cover butt jointsbetween adjacent tubbings 4, a comparatively higher extensibility withlower tensile strength can be chosen, which can be compared withdifferently thick steel cables for taking up different loads.

The first layer 2 a can consist of an elastic plastic for example andthe second layer 2 b of a tear-proof fabric. In particular, the secondlayer 2 b can concern a polyester, polyethylene, carbon or glass-fibergrid fabric. In accordance with a preferred embodiment, the first layer2 a can be connected at least in sections with the second layer 2 b,preferably laminated or glued onto the same.

On the one hand, in the course of mounting the lining 2 in accordancewith the invention, the fastening of the second layer 2 b with highertensile strength can be made to the tubbings 4 of the first shell 1 in afirst method step, and the fastening of the first layer 2 a with thehigher extensibility to the second layer 2 b in a second method step. Onthe other hand, the fastening of the lining 2 with the first layer 2 aand the second layer 2 b which were connected with each other at leastin sections in a preceding method step to the tubbings 4 can also bemade in a method step. This procedure is recommended when aprefabricated lining 2 with the two layers 2 a, 2 b for the lining ofthe inside walls of tunnels is already available.

The coating 2 in accordance with the invention can thus be used toprevent damage to the coating 2 and impairments in the watertightness byirregularities in the inside surface of the tunnel, preferably theinside surface of tubbings 4. The measures in accordance with theinvention represent a comparatively inexpensive solution and ensure inparticular that the time-consuming and expensive repair of concrete andplugging of the various depressions and openings such as joints, cones,pockets, flaked parts, holes of suspensions, tubings, etc. can beavoided.

1. An inside shell of a tunnel, comprising a lining (2) for an insidesurface of a tunnel, preferably the inside surface of tubbings, with thelining (2) comprising at least two layers of different tensile strengthand extensibility, wherein the lining (2) comprises two layers with afirst layer (2 a) consisting of an elastic plastic material with higherextensibility than the second layer (2 b), and the second layer (2 b)consists of a tear-proof fabric, and the first layer (2 a) is connectedto the second layer (2 b) at least in sections.
 2. An inside shell of atunnel comprising a lining (2) according to claim 1, wherein the secondlayer concerns a polyester, polyethylene, carbon or glass-fiber gridfabric.
 3. An inside shell of a tunnel comprising a lining (2) accordingto claim 1, wherein the first layer (2 a) is laminated or glued onto thesecond layer (2 b).